verb - To bail on your friends to hang out with your girlfriend. It is considered an especially bad case of Lammersing if the Lammerser in question planned the event with friends that he is Lammersing himself, far ahead of time, and then decided to Lammers WHILE AT THE EVENT.

"Why does he keep Lammersing on us? Can't he just tell us he's gonna hang out with her ahead of time instead of Lammersing at the last minute every time?"

A numbered, chip-like implement placed on a casino gaming table
indicating the amount of value chips that have been removed from a
table tray during a table credit slip transaction, or an amount of chips
that has been given to a customer for wagering on credit prior to
completion of a credit instrument (marker).

When the customer requested a marker for the remainder of his credit line, the pit boss put a 5000 lammer on the blackjack table and the dealer cut out $5000 in chips to give the player.